In a prime location in the nation's capitol, a six-story reinforced concrete building was to be converted into a luxurious condominium. To accommodate the building's new use, and the addition of pipes, ducts and conduits throughout the building floors, slab penetrations up to nine-inches in diameter and square openings up to 18-inches in dimension needed to be installed. The resulting loss in concrete section and reinforcing steel bars at penetrations caused deficient slab that would need to be strengthened.

Structural Preservation Systems (SPS) was approached by the client to provide a design-build upgrade for the slab openings. Several strengthening options were evaluated for this project, but the most effective proved to be the use of externally-bonded carbon fiber reinforced polymer (FRP) composites. First, the slab was cut as indicated on the drawings, and then the number and layout of the severed steel bars at each penetration was determined. The layout was submitted to the engineer-of-record in order to establish a strengthening criteria, and the details were then provided to SPS to design and install an appropriate strengthening repair using FRP composites. The amount and layout of FRP varied for each location depending on penetration size and location, as well as the number, size and layout of severed steel bars. An open channel of communication between the different teams working on this project facilitated the coordination of the various tasks and ensured a prompt response to arising and constantly changing field conditions.